Improve download files page layout

[nlhkabu]

Closes #18732

[nlhkabu]

WIP:

TODO:

• Update select to show values in "pretty" format - e.g. CP26 becomes CPython 2.6
• Update table to show values in "pretty" format - e.g. CP26 becomes CPython 2.6
• Show "No files match your selection" message when user filters by a combination which returns no results
• Limit the filters based on what the user has already selected
• Provide quick option to reset the filters (?)
• Update URL based on filters

[nlhkabu]

Question how should we format the ABI?

Example options for the ABI cp36m:

OR

OR

OR

[merwok]

IMO it should not be just m (pymalloc), but needs to include all the parts: m and other modifiers don’t make sense without the first part cp36.

Unless it’s guaranteed that an abi tag cp36m always has an interpreter tag of cp36, but I am not sure about that.

[nlhkabu]

Ok, thanks for your feedback @merwok, and for your comments on the associated issue.
I've added "Update URL based on filters" to the TODO list

re: ABIs, I've added a couple more options above - based on your feedback, I think the third option is best: CPython 3.6m (pymalloc)